There are different parts to this answer.

> since it doesn't use the core theme_breadcrumb() function.

By default, it should use theme('breadcrumb').
But you should have a look at the settings in admin/structure/crumbs/display.

But this being said, it is not really the job of theme('breadcrumb') to change a breadcrumb item title.

With Crumbs, every breadcrumb item title is provided by a plugin.
The plugins take these from menu links, from the title / title callback of the router item, or elsewhere.
In most cases there is already an existing plugin which provides the breadcrumb item title you need.

Otherwise you can write your own plugins. I can give you a hint about that, but I need more information where you want the special char to show up. (I will edit the answer then)